Process of and apparatus for making stencil sheets



Jan. 18 1927. 1,614,609

v J. D. GRANGE ET AL PROCESS OF AND APPARATUS FOR MAKING STENCIL SHEETSFiled Dec. 30. 22 2 Shets-Sheet 1 L I M Q a m I7ZU77757".5 Jo/ml].Grange Edward F [fosj/lra 0 YMW 7w Jan. 18 1927. 1,614,609

J. D. GRANGE ET AL PROCESS OF AND APPARATUS FOR MAKING STENCIL SHEETSfiver 1W3 Joh n D. Grange Edward]? Vps'ylra Patented Jan. 18, 1927.

UITED' STATES HP'ATENT OFFICE.

JOHN DOUGLASS GRANGE, OF BROOKFIELD, AND EDWARD FRANK.VOSYKA, OE CHI-CAGO, ILLINOIS. ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCORIORATED, OFNEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF AND APPARATUS FOR MAKING STENCIL SHEETS.

Application filed December 30, 1922. Serial No. 610,053.

This invention relates to means for and methods of making stencil blanksof the type described in the co-pending application of John DouglassGrange, Serial No. 603,125, filed-Nov. 24, 1922. U

Stencil blanks of this general type are made by impregnating sheets ofthin, open,

lace-like paper such as Japanese Yoshino paper or the like with aprotein impregnating compound.

Heretofore it has been the practice in making stencil blanks to placethe base sheet upon the surface of an impregnating bath, maintaining itin such a position until it is thoroughly impregnated with the mixtureand then withdrawing it in such a manner that any surplus solution isremoved and returned to the bath, the impregnated blank was then exposedto the light and allowed to dry.

It has been found that blanks produced )y this process are not alwaysuniform and are expensive to manufacture. culty encountered is due tothe imperfect contact between the tissue sheet and the surface of theliquid caused by the air or gas bubbles formed in the liquid by thereturn of the .surplus fluid to the bath. Another difficulty which hasbeen experienced is due to the cooling of the surface of theimpregnating bath and of the'tissue sheet when in contact with suchsurface thereby-congeal ing the solution too quickly on the sheet.

Some stencil blanks of the character-used prior to the inventiondescribed in the above mentioned co-pending application must besubjected to light for a considerable period of timewhile drying, whilewith the stencil blanks as described therein it is not necessary toexpose the sheets to the light, Thus it is possible to place them in adrying chamber immediately upontheir removal from the impregnatingsolution. In this way the drying of the sheets may be. materiallyhastened.

Objects of the invention are to improve the quality and to cheapen andexpedite the manufacture of stencil blanks of the impregnated type. p

Another objgct of the lnvention is to pre- 1 vent the intro uctio-n intoa body of liquid of air or gas bubbles present in a source of supply.

In order to secure these objects in accordcosity of the solution and theexcess solution is removed immediately upon the withdrawal of the blanksfrom the bathand any bubbles which may be formed by the removal aredissipated during the'return of the excess solution to the bath, so thatthey do not appear upon the surface thereof. In this manner. uniformcontact of the tissue with the solution is insured. The blanks are thensupported in conveniently arranged frames which are placed in a dryingoven or chamber. When' completely dried a plurality of the frames may beplaced upon a suitable support and the stencils removed by cutting orotherwise.

These and other features of the invention will appear from the followingspecification and the accompanying drawings, of which:

Fig. 1 shows the general arrangement of the apparatus;

Fig. 2 is a plan of the section of the impregnating unit;

Fig. 3 is a fragmentary end view in section of such unit; K Fig. 4 is anenlarged view also in section of a portion of Fig. 3, and

Fi 5 shows a side view in cross section of the receptacle containingimpregnating solution as well as an impregnating blank which is beingwithdrawn.

An impregnating unit designated generally by the character A is placedupon a suitable table which may be provided withcastors or wheels forpermitting its movement on the floor, as shown, or over a track orrunway, in'proximity to a drying chamber or oven B. The impregnatingunit contains character described in the above mentioned co-pendingapplication. A door 20 is pro- .vided in the side of the unit to permitaccess to the tray 10 for pouring impregnating solution into the tray,while a door 21 is provided for giving access to a tank 22 within whichan extra supply of solution is kept.

Underneath the tank 22 is placed an electrical heating element 23 of anysuitable type, which may beconnected in any well known manner with asource of current for controlling the temperature of the solution sothat the compound is maintained at the desired viscosity. Below theelement 23 a compartment is provided within which a workin supply ofsheets of tissue 25 may be kept. ilnderneath the receptacle 10 anotherelectrical heating element 26 is provided for maintaining the workingsupply of the impregnating solution at a desired tempera ture.

It will be noted that the element 26 extends beyond the sides of thetray 10, and that metal shields 27 extending upwardly on the edge 'ofthe element turn inwardly and downwardly fromthe sides and the reare endof the tray in such a way that currents of heated air produced byheating element 26 are directed to the surface of the solution thusinsuring that such sur face is maintained at substantially the sametemperature and viscosity as the other portions of the bath. Since indrawing the tissue sheet across the surface the rear end of the sheetmay not immediatelycont-act with the surface it is especially importantthat the surface be properly heated at this point. At the outer end ofthe tray 10, a scraper 28 preferably of wirev is provided, one end ofwhich is suitably anchored by means of solder or arivet and the otherend of which is provided with a thumb screw 29 or other means formaintainin the wire taut. This wire 28 is provided or removing thesurlus solution from the stencil blank 30 as It is being withdrawn fromthe tray 10.

Such surplus solution drops into a receiver 31 formed b the ends of thetray and wall 32. A plura it of openings 33 of very small size ar'eprovi ed in the lower end of such wall for the interchange of thesolution in the two compartments of the tray.

The wall 32 having the restricted openinis 33 provides what may becalled a bu ble dam. If this meansf'were not provided as the surplussolution flows into the working supply of solution any air or gasbubbles formed by the removal of the surplus solution from the blank orthe dropping of such solution into the receiver 31 would rise to thesurfaceof the solution and mi ht prevent contact between the'solution ansheets of. tissue subsequently placed in the bath.

The impre nating unit A is also provided with a suitable exhaust pipe 40through which the fumes which may be formed by the impregnatingsolution. will be carried away by means of a power driven fan orotherwise. An ordinary incandescent lamp 41 connected with any suitablesource of electr cal current is provided for properly illuminating theinterior of the unit, and

a. glass plate 42 placed at a convenient angle allows the properobservation of tho impregnating process.

A suitable frame 43 which may be of wood and arranged for the reception.of a plurality of impregnated stencil blanks 30, is further adapted forinsertion in a post formed at the-side of the impregnating unit A. Theplacing of the frame in a convenient position for receiving the blanksas they are taken from the impregnating bath has been found to be veryuseful. A triangular block 45 attached to the side of the unit A isprovided-with a. vertical slot 46, in the front end thereof for thereception of the end post 47 of the frame 43: A button 49 is pivot-ed inany suitable manner by means of a pin 50 or otherwise on the block 45.The portion 51 of the button extending over the slot 46 is preferablymade of greater length than the remaining portion so that when normallythe greater weight of portion 51 causes the button to assume a verticalposition, when the post 47 of the frame 43 is placed in the slot 46, thebutton is turned until the portion 51 of the button extends across theslot and rests upon the upper surface of the lower horizontal member ofthe frame. 'The button is held in this position by gravity securelylocking the frame in the block 45. When it is desired to remove theframe it is simply .lifted, swinging the portion 51 of the button upbythe heating pipes which may contain steam or water or suitable heatingmeans. An exhaust pipe 71 provides for the taking away of the moistureandinsures the proper circulation of air within the chamber while thedrying process is proceeding. A series of horizontal members 72 areprovided upon "which the frames 43 are placed in vertical position whenremoved from the impregnating unit A. Sliding doors 73 are provided inthe slide of the drying oven to permit ready access to the interiorthereof.

A'movable carriage 75 is provided which travels upon suitable tracks 76by means of rollers 77, such carriage being provided with verticalsupports 78 against which the frames 43 may be placed upon their removalfrom the chamber, and a horizontal portion 79 for carrying a receptacle.or tray 80 in which the completed stencil blanks.

are placed upon their removal from the" The remaining compound is keptin thetank 22'and is also maintained at approximately the'sametemperature.-

Theoperator grasps a sheet of tissue in the supply 25 by its corners,draws it over the surface of'the impregnating bathin the tray 10, andthereafter over the scraper 28, which removes the excess-solution fromthe sheet. It has been found that it is not necessary to keep the sheetin the bath for any longer period of time than that which is occupied bythe drawing of the sheet over the surface.

The coated sheet is then placed on the frame 43 and attached by means ofthe compound to the upper and lower horizontal members of such frame.After the frame 43 is filled with blanks, the frame is removed thechamber B from its support at the side of the impregnating unit and isplaced vertically upon the horizontal bars 7 2 of the drying chamber B.Another frame is then placed in proper position at the side of theimpregnating unit A for the reception of additional coated blanks. Ithas been ,found desirable to coat the frames witha mixture of equalparts of paraflin and beeswax to insure the'proper attaching of theimpregnating blank thereto.

It will be noted that the. unit A may be: readily moved along the sideof the drying chamber B and that the sliding doors 73 of rovide accessto the chamber at any point. n this manner the operator may start withthe unit A at one end of the chamber B, place the frames 43 in that endof the chamber and move the unit A toward the opposite end as thechamber becomes filled with the frames. When the stencil blanks becomethoroughly dried several of the frames L3 may be removed and laced inthe roper manner on the carriage 5. The

blan s may be readily removed from several frames simultaneously by.cutting along the lower edge of the upper horizontal members and alongthe upper edge of the lower horizontal members of the several frames.The empty frames are then placed'in the chamber B for future use, itbeing unnecessary to remove the marginal portions attached to the upperand lower horizontal members each time the frames aroused, since thefreshly impregnated sheets will readily adhere to such portions. Thesemarginal portions may be removed at the convenience of the operator.

- The finished blanks as they are removed from the frames are depositedin the tray 80, from which they may be; removed and attached to suitablemanila paper backing sheets preparatory to being stencilized.

By following this process and employing the structuresshown in thedisclosed embodiment of the invention the manufacture. of stencil blanksis materially hastened and cheapened and a uniform product is assured.It has been found that if the interior of the drying chamber ismaintained at a temperature of approximately 95 Fahrenheit and tion ofthe 9.11 within the chamber this period may be greatly reduced. However,stencils heretofore proposed wherein the coagulation of the impregnatingcompound is dependent upon exposure to light cannot be made in less thansixhours and under unfavorable light conditions may require twelve hoursfor their completion.

lVhat is claimed is:

1. In an impregnating device. a tray for holding impregnatingcompound,'a scraper associated with the tray for removing the surpluscompound'from the article treated, a receiver for the surplus compoundand a restricted connection between the receiver and the tray. fordissipating bubbles in the surplus compound.

2. In an impregnating machine, a receptacle for holding impregnating.compound 1 in such manner that an article may be rest- 7 ed en thesurface of'the compound, and means for supplying a current of heated airto the article while resting on the surface of the compound.

3. In an impregnatin machine, an open receptacle for holding lmpregnatincompound in such manner that anartic e may be rested on the surface ofthe compound, means for supplying a current of heated air to the articlewhile resting on the surface of the compound, and means for heating thecompound in the receptacle.

4-. In an impregnating machine, an open receptacle for holdingimpregnating compound, and common means for heating separately theplying heat directed to the upper surface thereof.

body of the compound and sup- 5. In an impregnating machine, an open 6.In an impregnating machine, an open receptacle, for holding impregnatlngcom pound, a heating element for heating the compound, and means fordirecting heated currents of air from the element to the surface of thecompound.

7. In a'receptacle for liquids,

auxil ary portion and having a restricted opening to permit interchangeof liquid bea wall diriding the receptacle into amain and an whichcomprises maintaining a compound sheet, attaching the sheet to asupport, placing the supported sheet in a drying chamber, subjecting thesupported sheet to a con stant temperature and removing the driedstencil blank from the oven.

9. In an impregnating machine, an open receptacle for holding animpregnating compound, a member dividing said receptacle into a main andan auxiliary portion having an aperture connecting the two portionswhereby compound in the auxiliary portion may be returned to the mainportion without disturbing the surface of the com pound containedtherein, and means mounted. over the auxiliary portion and offset fromsaid member for'returning to said auxiliary portion excess compoundremoved from the impregnated article.

In witness whereof, we hereunto subscribe our names this 20 day ofDecember A. 1)., 1922.

JOHN DOUGLASS GRANGE. EDWARD FRANK VOSYKA.

